4is0
From Proteopedia
Structural Insights into Omega-Class Glutathione Transferases: A Snapshot of Enzyme Reduction and Identification of the Non-Catalytic Ligandin Site.
Structural highlights
FunctionGSTO1_HUMAN Exhibits glutathione-dependent thiol transferase and dehydroascorbate reductase activities. Has S-(phenacyl)glutathione reductase activity. Has also glutathione S-transferase activity. Participates in the biotransformation of inorganic arsenic and reduces monomethylarsonic acid (MMA) and dimethylarsonic acid.[1] [2] [3] [4] [5] Publication Abstract from PubMedGlutathione transferases (GSTs) are dimeric enzymes containing one active-site per monomer. The omega-class GSTs (hGSTO1-1 and hGSTO2-2 in humans) are homodimeric and carry out a range of reactions including the glutathione-dependant reduction of a range of compounds and the reduction of S-(phenacyl)glutathiones to acetophenones. Both types of reaction result in the formation of a mixed-disulfide of the enzyme with glutathione through the catalytic cysteine (C32). Recycling of the enzyme utilizes a second glutathione molecule and results in oxidized glutathione (GSSG) release. The crystal structure of an active-site mutant (C32A) of the hGSTO1-1 isozyme in complex with GSSG provides a snapshot of the enzyme in the process of regeneration. GSSG occupies both the G (GSH-binding) and H (hydrophobic-binding) sites and causes re-arrangement of some H-site residues. In the same structure we demonstrate the existence of a novel "ligandin" binding site deep within in the dimer interface of this enzyme, containing S-(4-nitrophenacyl)glutathione, an isozyme-specific substrate for hGSTO1-1. The ligandin site, conserved in Omega class GSTs from a range of species, is hydrophobic in nature and may represent the binding location for tocopherol esters that are uncompetitive hGSTO1-1 inhibitors. Structural insights into omega-class glutathione transferases: a snapshot of enzyme reduction and identification of a non-catalytic ligandin site.,Brock J, Board PG, Oakley AJ PLoS One. 2013 Apr 9;8(4):e60324. doi: 10.1371/journal.pone.0060324. Print 2013. PMID:23593192[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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